Furnace Atomic Absorption Spectrometry Detection Research Articles

Determination of Vanadium(IV) and Vanadium(V) in Beverages by Two-Step Direct Immersion Single-Drop Microextraction with Graphite Furnace Atomic Absorption Spectrometry (GFAAS)

A novel two-step direct immersion single-drop microextraction (TS-DI-SDME) was reported for the sequential separation and enrichment of V(V) and V(IV) followed by graphite furnace atomic absorption spectrometry detection. Theonyltrifluoroacetone (HTTA) and chloroform were used as the chelating reagent and extraction solvent for TS-DI-SDME. In the first step, V(V)-HTTA complexes were separated and enriched in one organic solvent drop at pH 2.5, while V(IV) remained in the solution. Next, another organic solvent drop containing HTTA was immersed in the original solution after the extraction of V(V) for the enrichment of V(IV) at pH 4.5. This procedure avoids tedious and complicated pre-oxidation/pre-reduction operations, which may cause contamination and error. Under the optimized conditions, the limits of detection were equal to 3.1 and 2.6 ng L−1 for V(IV) and V(V) with relative standard deviation values of 4.9 and 5.8%, respectively. An enrichment factor of 300-fold was achieved for V(IV) and V(V). This method was successfully utilized for the determination of V(IV) and V(V) in beverages. To validate this approach, a water-certified reference material was analyzed with satisfactory results.

Determination of Tl(III) and Tl(I) in food samples with two-step direct immersion single-drop microextraction followed by graphite furnace atomic absorption spectrometry

In this study, a new procedure of two-step direct immersion single-drop microextraction (TS-DI-SDME) was firstly developed for the sequential separation and enrichment of Tl(III) and Tl(I) before graphite furnace atomic absorption spectrometry detection. At pH 6.0, Tl(III) selectively reacts with 1-(2-Pyridylazo)− 2-naphthol to form the complexes which can be extracted into one organic drop, while Tl(I) remained in the solution. Then, another organic drop containing dicyclohexano-18-crown-6 was immersed in the sample solution after the extraction of Tl(III) for the enrichment of Tl(I) at the same pH value. Main parameters affecting the separation and enrichment of Tl species were investigated. Under optimized conditions, limits of quantification (LODs) were 6.3 ng L−1 and 8.3 ng L−1 for Tl(III) and Tl(I), respectively. Repeatability and reproducibility were assessed by calculating relative standard deviations (RSDs), which were less than 5.1% and 6.7% for Tl(III) and Tl(I), respectively. Preconcentration factors of 300-fold were achieved for Tl species. This method was used successfully for the determination of Tl(III) and Tl(I) in food samples. To validate this procedure, a certified reference material of milk powder was analyzed with the satisfactory results. This method may avoid the problems of tedious operations, sample contamination and analysis errors in redox speciation strategies.

Solidified floating organic drop microextraction in tandem with syringe membrane miro-solid phase extraction for sequential detection of thallium (III) and thallium (I) by graphite furnace atomic absorption spectrometry

In the present study, a novel method based on solidified floating organic drop microextraction (SFODME) combined with syringe membrane micro-solid phase extraction (SMMSPE) was proposed for the sequential separation and enrichment of Tl(III) and Tl(I) followed by graphite furnace atomic absorption spectrometry detection. In SFODME, Tl(III) can react with 1-(2-Pyridylazo)-2-naphthol at pH 8.0 to form the complexes which can be extracted into an organic drop, while Tl(I) was remained in the solution. In SMMSPE, flexible TiO2@SiO2 nanofiber membrane was used as the sorbent for the enrichment of Tl(I) in the sample solution after the separation of Tl(III). This method did not require tedious pre-oxidation/pre-reduction operation and time-consuming centrifugation/filtration steps, which may cause sample contamination and analysis errors. Main parameters influencing the separation and enrichment of the target species were studied. Under the selected conditions, the detection limits for this method were 1.7 and 2.6 ng/L for Tl(III) and Tl(I) with relative standard deviations of 6.1 % and 5.2 %, respectively. This method was successfully used for the determination of the target species in environmental water samples and two certified reference materials. The determined values were in good agreement with the certified values.

Direct immersion dual-drop microextraction for simultaneous separation and enrichment of Cr(III) and Cr(IV) in food samples prior to graphite furnace atomic absorption spectrometry detection

Non-chromatographic speciation methods generally involve speciation conversion, which may cause sample contamination, analysis errors and tedious operations. In this work, a direct immersion dual-drop microextraction (DIDDME) was firstly developed for separation and preconcentration of Cr(III) and Cr(VI). In DIDDME, two organic drops on needle tips of microsyringes were concurrently immersed in a stirred sample solution. Each drop contains a chelating reagent for reacting with a specific species. Thus, Cr(III) and Cr(VI) were selectively extracted into different drops. This method afforded detection limits of 3.0 and 4.1 ng/L, quantification limitof 10 ng/L and 14 ng/L, linear range of 0.01–30 ng mL−1 and enrichment factors of 354-fold and 326-fold for Cr(III) and Cr(VI), respectively. Precisions like repeatability and reproducibility were assessed by calculating relative standard deviations, which were lower than 5.4 % and 6.9 %, respectively. This procedure was used successfully for quantification of Cr(III) and Cr(VI) in food samples.

A novel separation and preconcentration methodology based on direct immersion dual-drop microextraction for speciation of inorganic chromium in environmental water samples

In this study, for the first time, a novel separation and preconcentration method of direct immersion dual-drop microextraction (DIDDME) was proposed for the species of inorganic chromium (Cr(III) and Cr(VI)) followed by graphite furnace atomic absorption spectrometry detection. The methodology is based on that two organic drops hold on the needle tips of microsyringes were concurrently immersed in a stirred sample solution. Each drop contains a chelating reagent, which can react with a specific species under the same pH value. Therefore, Cr(III) and Cr(VI) can be selectively extracted into different drops. This procedure did not require tedious and complicated pre-oxidation/pre-reduction and centrifugation/filtration operations, which may lead to the risk of sample contamination and analysis errors. Main parameters influencing separation, preconcentration and identification of the target species were investigated. An enrichment factor of 400-fold was obtained for Cr(III) and Cr(VI). Under the optimized conditions, detection limits for this method were 1.1 ng L−1 and 1.4 ng L−1 for Cr(III) and Cr(VI) with relative standard deviations of 5.1 and 6.3%, respectively. This procedure was applied for the separation, preconcentration and determination of Cr(III) and Cr(VI) in environmental water samples and certified reference materials with satisfactory results. Recoveries of spiked experiments ranged from 86.0 to 112%.

Speciation of inorganic vanadium by direct immersion dual-drop microextraction coupled with graphite furnace atomic absorption spectrometry detection

In this work, a new method based on direct immersion dual-drop microextraction (DIDDME) was proposed for simultaneous speciation and enrichment of V(IV) and V(V) by graphite furnace atomic absorption spectrometry. This strategy was initiated with the chelation of V(IV) and V(V) in sample solutions with 1-(2-Pyridylazo)-2-naphthol (PAN). In the following step, two organic solvent drops hold on needle tips of microsyringes were concurrently immersed in the stirred sample solution to selectively and simultaneously separate V(IV)-PAN and V(V)-PAN complexes under the same pH value. This procedure avoided the tedious and complicated pre-oxidation/pre-reduction and centrifugation/filtration operations, which may cause the risk of sample contamination and analysis errors. Main parameters affecting the separation, preconcentration of the target species were investigated. Under the optimized conditions, the detection limits of this method were 2.4 ng/L and 1.5 ng/L for V(IV) and V(V) with relative standard deviations of 6.1 and 5.3 %, respectively. An enrichment factor of 300-fold was achieved for V(IV) and V(V). This method was applied successfully for the determination of V(IV) and V(V) in water samples. In order to validate the proposed procedure, a certified reference material of water sample was analyzed, and the determined value was in good agreement with the certified value.

Facile green synthesis of magnetic porous organic polymers for fast preconcentration of trace lead and mercury from environmental water followed by graphite furnace atomic absorption spectrometry detection

Magnetic porous organic polymers (MPOPs) was synthesized in aqueous phase under mild condition by using Fe3O4@SiO2 nanoparticles as magnetic core, 1,3,5-tris-(4-aminophenyl) benzene (TAPB) and 4-(2-pyridylazo) resorcinol (PAR) as two building blocks. The resultant materials (denoted as TAPB-PAR-MPOPs) have the features of good magnetism, high porosity and large surface area, and fast adsorption kinetic (8 min) as well as high adsorption capacities (319 and 374 mg g−1, respectively) toward lead and mercury ions. With the prepared TAPB-PAR-MPOPs as sorbent, a method of magnetic solid phase extraction coupled with graphite furnace atomic absorption spectrometry was developed for the determination of trace lead and mercury in environmental water samples. Under the optimal conditions, the detection limits were 0.009 and 0.017 μg L−1 for lead and mercury, respectively. The developed method was successfully applied to the analysis of trace lead and mercury in tap water, lake water and river water samples with satisfactory recoveries (88.3–107%), demonstrating a good potential of TAPB-PAR-MPOPs in extraction of trace lead and mercury in environmental waters.

Syringe Membrane Micro-Solid-Phase Extraction (SPE) with Flexible Titanium(IV) Oxide@Silica Nanofiber Membrane for the Speciation of Te(IV) and Te(VI) with Graphite Furnace Atomic Absorption Spectrometry (GFAAS)

In this work, syringe membrane micro-solid phase extraction (SMMSPE) was described for the enrichment and separation of Te(IV) and Te(VI) prior to graphite furnace atomic absorption spectrometry detection. SMMSPE device is composed of a syringe and a disk filter, which was filled with flexible titanium(IV) oxide@silica nanofiber membrane as the sorbent. The adsorption behavior of Te(IV) and Te(VI) on the sorbent was studied in detail. The results showed that Te(IV) was quantitatively adsorbed on the sorbent in the pH range of 3.0-5.0, while Te(VI) remained in the aqueous phase. Te(VI) content was obtained by subtracting Te(IV) from total Te concentration. Total Te was detected after reducing Te(VI) into Te(IV). The key factors affecting the extraction efficiency and determination of target species were investigated. Under the selected conditions, the limit of detection was 1.8 ng L−1 for Te(IV). The precision expressed as relative standard deviation was 5.7% (n = 9). This method was utilized for the determination of Te(IV) and Te(VI) in environmental water samples with satisfactory results. To verify this method, a certified reference material of water sample was analyzed, and the obtained result was in good agreement with the certified value. Besides, the developed sorbent exhibited good efficiency, flexibility and recyclability.

Emulsion breaking-induced extraction of Cd and Pb from oily dietary supplements followed by graphite furnace atomic absorption spectrometry detection

A method is described for the determination of cadmium (Cd) and lead (Pb) in oily dietary supplements using extraction induced by emulsion breaking (EIEB) and high-resolution continuum-source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). The method is based on the formation of a water-in-oil emulsion by the addition of an extractor solution consisting of 5 % (w/v) Triton X-100% and 15 % (v/v) hydrochloric acid (HCl) to the sample of oil diluted with 1.5 mL of toluene and the breakage of this emulsion by centrifugation (4000 rpm for 5 min). Two well-defined phases were formed and the acid aqueous phase containing extracted Cd and Pb ions was analyzed by HR-CS GFAAS. Different parameters that influence the extraction efficiency of Cd and Pb were optimized univariately. The detection limits were 3.32 μg kg−1 for Pb and 1.51 μg kg−1 for Cd. A matrix-based calibration method was applied to compensate for the interference caused by the matrix effects. The Cd concentration in the samples ranged from 8.81 to 9.35 μg kg−1 and the highest concentration of Pb was 19.91 μg kg−1. The proposed preparation of sample through extraction by breaking emulsions of oily dietary supplements proved to be a simple and efficient strategy to determine the amount of Pb and Cd by HR-CS GFAAS.

Speciation of As(III) and As(V) in Food by Magnetic Dispersive Microsolid Phase Extraction with Dispersive Liquid–Liquid Microextraction with Graphite Furnace Atomic Absorption Spectrometry (GFAAS) Detection

Magnetic dispersive microsolid phase extraction (MDMSPE) was coupled with dispersive liquid–liquid microextraction (DLLME) for the separation and preconcentration of arsenic(V) and arsenic(III) prior to graphite furnace atomic absorption spectrometry detection. In the first step, magnetic ZnFe2O4 nanotubes were employed for adsorbing arsenic(V). The adsorbent was separated from the aqueous phase by the use of an external magnetic field. Next, arsenic(III) in the upper aqueous phase from MDMSPE was enriched by DLLME. Samples were prepared with artificial gastric juice to avoid inter-conversion of the determined species. The parameters affecting the separation and preconcentration of the determined species were optimized. The detection limits of this protocol were determined to be 1.3 and 2.0 pg mL − 1 for arsenic(III) and arsenic(V) with relative standard deviations of 4.5% and 5.6% for a concentration of 1.0 ng mL − 1 (n = 9). The enrichment factors were equal to 175-fold for arsenic(III) and 163-fold for arsenic(V). The developed protocol was employed for the determination of arsenic(III) and arsenic(V) in dairy products without preoxidation or prereduction. The recoveries of spiked samples were from 90.8% to 105%. A milk powder certified reference material was analyzed by this approach and the measured results were in good agreement with the certified value.

Fe3O4 nanoparticles coated with double imprinted polymers for magnetic solid phase extraction of lead(II) from biological and environmental samples.

Double imprinted polymer coated magnetic nanoparticles were fabricated with 4-nm size ZnO nanoparticles acting as the sacrifice templates, which were co-imprinted with template Pb(II) ions. After template removal, abundant transfer pores derived from ZnO nanoparticles were left around the selective adsorption sites derived from Pb(II) ions. The magnetic sorbent exhibit good selectivity, rapid adsorption kinetic and large adsorption capacity for Pb(II). They were used to extract trace Pb(II) followed by graphite furnace atomic absorption spectrometry detection. After the optimization of extraction conditions, following merits are found: (a) rapid extraction (10min), (b) high preconcentration factor (100 fold), (c) sensitive detection with the detection limit of 9.4ng·L-1, and (d) low relative standard deviation (6.9%) at a level of 50ng·L-1 of Pb(II) analyzed 7 times. The method was employed in extraction and quantification of trace Pb in biological and environmental samples with satisfactory recoveries of 87.5-104%. Graphical abstractDouble imprinted polymer coated magnetic nanoparticles (MNPs@DIP) were fabricated and used for extraction of Pb(II) followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. The method was successfully applied for the determination of Pb in environmental and biological samples.

Switchable solvent based liquid phase microextraction of trace lead and cadmium from environmental and biological samples prior to graphite furnace atomic absorption spectrometry detection

A switchable hydrophilicity solvent (SHS) based liquid phase microextraction (LPME) method was proposed for the preconcentration of trace Pb (II) and Cd (II) followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. The SHS of protonated triethylamine carbonate (P-TEA-C) was synthesized and applied as the extractant, which is environmentally friendly and low cost. Pb (II) and Cd (II) in ammonium pyrrolidine dithiocarbamate (APDC) complex form was extracted into the triethylamine (TEA) phase by converting P-TEA-C to TEA. The vortex led to the rapid formation of fine droplets of the extractant in the aqueous solution, and enlarged contact surface between both immiscible liquids. The factors affecting the microextraction procedure, including sample pH, APDC concentration, volume of SHS and NaOH, sample volume and matrix effect were investigated. Under the optimal conditions, enrichment factor of 50 was achieved with consumption of 10mL aqueous sample, and detection limits of 16 and 3.9ngL−1 were obtained for Pb (II) and Cd (II), respectively. The accuracy of the proposed method was validated by the analysis of Certified Reference Materials of GSBZ50009-88 environmental water, GBW07605 tea and GBW07601(GSH-1) human hair. The method was also successfully applied for determination of Pb (II) and Cd (II) in water, tea and human hair samples.

Poly(1-vinylimidazole) functionalized magnetic ion imprinted polymer for fast and selective extraction of trace gold in geological, environmental and biological samples followed by graphite furnace atomic absorption spectrometry detection

In this study, poly(1-vinylimidazole) functionalized gold ion imprinted polymer coated magnetic nanoparticles (MNPs@PVIM-Au-IIP) were prepared and characterized. The adsorption behaviors of the prepared MNPs@PVIM-Au-IIP toward gold ions (Au(III)) were studied, it was found that MNPs@PVIM-Au-IIP has good selectivity, high adsorption capacity (185.4mgg−1) and fast adsorption kinetic for Au(III). Based on it, a new method of ion imprinted magnetic solid phase extraction (II-MSPE) coupled with graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the analysis of trace Au(III) in real samples with complicated matrix. Factors affecting MSPE including sample pH, desorption reagent, elution concentration and volume, elution time, sample volume and adsorption time were optimized. With high enrichment factor of 100-fold, the detection limit of the proposed method is 7.9ngL−1 for Au(III) with the relative standard deviation of 7.4% (c=50ngL−1, n=7). In order to validate the accuracy of the proposed method, the Certified Reference Material of GBW07293 geological sample (platinpalladium ore) was analyzed, and the determined value was in good agreement with the certified value. The proposed II-MSPE-GFAAS method is simple, fast, selective, sensitive and has been successfully applied in the determination of trace Au in ore, sediment, environmental water and human urine samples with satisfactory results.

In situ-produced CO2-assisted dispersive liquid–liquid microextraction for extraction and preconcentration of cobalt, nickel, and copper ions from aqueous samples followed by graphite furnace atomic absorption spectrometry determination

In the present work, a new microextraction technique, namely in situ-produced CO2-assisted dispersive liquid–liquid microextraction was introduced for the extraction and preconcentration of cobalt, nickel, and copper from aqueous samples followed by graphite furnace atomic absorption spectrometry detection. The proposed method relies on the CO2 gas produced due to a chemical reaction as the disperser agent instead of the disperser solvent used in the conventional dispersive liquid–liquid microextraction. Initially, a solid mixture of tartaric acid and sodium bicarbonate was placed in the bottom of a dry conical glass test tube. Then µL level of 1,1,2,2-tetrachloroethane as the extraction solvent was added into the tube. An aqueous solution of the analytes containing sodium diethyldithiocarbamate (as chelating agent) was transferred into the tube. The reaction between tartaric acid and sodium bicarbonate was immediately occurred, and the produced CO2 led to dispersion of the extraction solvent as tiny droplets into the sample which resulted in extraction of the analytes into the organic solvent. The cloudy solution was centrifuged, and the sedimented phase was analyzed by the instrumental analytical method. Under the optimum conditions, the calibration curves were linear in the ranges of 20–300, 20–200, and 15–250 ng L−1 for Co2+, Ni2+, and Cu2+, respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 2.3 to 4.6 and 4.5–5.6% for intra- and inter-day (n = 6, C = 50 ng L−1) precisions, respectively. Moreover, the detection limits and enrichment factors of the selected analytes were obtained in the ranges of 6.2–12 and 139–150 ng L−1, respectively. The accuracy of the developed procedure was checked by analyzing NRCC-SLRS4 Riverine water as a certified reference material. Finally, the proposed method was successfully applied for the simultaneous analysis of the selected analytes in environmental water and fruit juice samples. The relative recoveries obtained for the analytes in the spiked samples were within in the range of 84–107%.

Iminodiacetic acid functionalized magnetic nanoparticles for speciation of Cr(iii) and Cr(vi) followed by graphite furnace atomic absorption spectrometry detection

In this work, iminodiacetic acid (IDA) functionalized magnetic nanoparticles (Fe3O4@SiO2@IDA) were prepared and the adsorption behavior of Cr(iii)/(vi) on them was investigated.

A sensitive magnetic nanoparticle-based immunoassay of phosphorylated acetylcholinesterase using protein cage templated lead phosphate for signal amplification with graphite furnace atomic absorption spectrometry detection.

We developed a new magnetic nanoparticle sandwich-like immunoassay using protein cage nanoparticles (PCN) for signal amplification together with graphite furnace atomic absorption spectrometry (GFAAS) for the quantification of an organophosphorylated acetylcholinesterase adduct (OP-AChE), the biomarker of exposure to organophosphate pesticides (OPs) and nerve agents. OP-AChE adducts were firstly captured by titanium dioxide coated magnetic nanoparticles (TiO2-MNPs) from the sample matrixes through metal chelation with phospho-moieties, and then selectively recognized by anti-AChE antibody labeled on PCN which was packed with lead phosphate in its cavity (PCN-anti-AChE). The sandwich-like immunoreaction was performed among TiO2-MNPs, OP-AChE and PCN-anti-AChE to form a TiO2-MNP/OP-AChE/PCN-anti-AChE immunocomplex. The complex could be easily isolated from the sample solution with the help of magnet, and the released lead ions from PCN were detected by GFAAS for the quantification of OP-AChE. Greatly enhanced sensitivity was achieved because PCN increased the amount of metal ions in the cavity of each apoferritin. The proposed immunoassay yielded a linear response over a broad range of OP-AChE concentrations from 0.01 nM to 2 nM, with a detection limit of 2 pM, which has enough sensitivity for monitoring of low-dose exposure to OPs. This new method showed an acceptable stability and reproducibility and was validated with OP-AChE spiked human plasma.

Novel ion imprinted magnetic mesoporous silica for selective magnetic solid phase extraction of trace Cd followed by graphite furnace atomic absorption spectrometry detection

Determination of trace Cd in environmental, biological and food samples is of great significance to toxicological research and environmental pollution monitoring. While the direct determination of Cd in real-world samples is difficult due to its low concentration and the complex matrix. Herein, a novel Cd(II)-ion imprinted magnetic mesoporous silica (Cd(II)-II-MMS) was prepared and was employed as a selective magnetic solid-phase extraction (MSPE) material for extraction of trace Cd in real-world samples followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. Under the optimized conditions, the detection limit of the proposed method was 6.1ngL−1 for Cd with the relative standard deviation (RSD) of 4.0% (c=50ngL−1, n=7), and the enrichment factor was 50-fold. To validate the proposed method, Certified Reference Materials of GSBZ 50009–88 environmental water, ZK018-1 lyophilized human urine and NIES10-b rice flour were analyzed and the determined values were in a good agreement with the certified values. The proposed method exhibited a robust anti-interference ability due to the good selectivity of Cd(II)-II-MMS toward Cd(II). It was successfully employed for the determination of trace Cd(II) in environmental water, human urine and rice samples with recoveries of 89.3–116%, demonstrating that the proposed method has good application potential in real world samples with complex matrix.

Speciation of organic and inorganic selenium in selenium-enriched rice by graphite furnace atomic absorption spectrometry after cloud point extraction

A new method was developed for the determination of organic and inorganic selenium in selenium-enriched rice by graphite furnace atomic absorption spectrometry detection after cloud point extraction. Effective separation of organic and inorganic selenium in selenium-enriched rice was achieved by sequentially extracting with water and cyclohexane. Under the optimised conditions, the limit of detection (LOD) was 0.08μgL−1, the relative standard deviation (RSD) was 2.1% (c=10.0μgL−1, n=11), and the enrichment factor for selenium was 82. Recoveries of inorganic selenium in the selenium-enriched rice samples were between 90.3% and 106.0%. The proposed method was successfully applied for the determination of organic and inorganic selenium as well as total selenium in selenium-enriched rice.

Determination of Trace Nickel in Hydrogenated Cottonseed Oil by Pressurized Bomb Acid Digestion and Graphite Furnace Atomic Absorption Spectrometry Detection

AbstractsA pressurized polytetrafluoroethylene (PTFE) bomb method for the digestion of trace nickel in hydrogenated cottonseed oil prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS) has been developed. Currently, the methods outlined in United States Pharmacopeial 28 (USP28) and British Pharmacopeial (BP2003) methods are recommended as the official methods for analyzing nickel in hydrogenated cottonseed oil. However, when using these methods, the samples were easily tarnished during sample pretreatment when using a silica crucible. In contrast, when using a platinum crucible, hydrogenated cottonseed oil acting as a reducing material may react with the platinum and destroy the crucible. In order to avoid the tarnish with a silica crucible and the risk when using platinum, the technology of a pressurized PTFE bomb method was applied in the digestion of nickel in hydrogenated cottonseed oil. The results showed that hydrogenated cottonseed oil can be digested completely by the optimal combinations of HCl (0.1 mL) and HNO3 (0.5 mL). The digested solution was investigated using graphite furnace atomic absorption spectrometry.